ABBAS'SIDES, The (Ar. al-‘Abbasiyjah). Caliphs of Bagdad, and the most celebrated Moslem dynasty, although their rule never extended over the whole of Islam, as had that of the Ommiads (q.v.). It was never acknowledged in Spain and only nominally in Africa outside of Egypt. Theirs was, however, the true caliphate, notwithstanding the rival claims of Cordova. The Abbassides claimed descent from Abbas, the uncle and adviser of Mohammed (566-652 A.D.). The rivalry between the family of Abbas and the Ommiads broke out into open war. In 747 Ibrahim, the head of the Abbasside faction, was overthrown by the Caliph Merwan and put to death, but three years later his brother, Abu al-Abbas, who had proclaimed himself rightful Caliph, defeated Merwan in a great battle near the river Zab and established his line firmly on the throne. In Spain, however, Abd al-Rahman, one of the Ommiads, who had escaped from the general destruction of his house, succeeded in establishing the great independent emirate, or kingdom (subsequently caliphate) of Cordova. It was long before the rulers of Spain assumed the title of Caliph. The successor of Abu al-Abbas, Almansur, made Bagdad the capital of his empire. Under his followers the empire enjoyed comparative peace and attained to a splendid development. The caliphs became the patrons of literature, art, and learning, and their courts were the homes of the most extreme luxury. The caliphs Harun al-Rashid (786-809) and al-Mamun (813-833) were famous throughout the world for their wealth, their splendor, and their munificence. But the martial vigor of the Arabs was sapped by the influence of Persian luxury, and they gradually ceased to be relied upon for military service. In Africa and in the northeastern part of Persia, emirs seized the opportunity to declare themselves independent; in the west the Greek Empire showed a revival of energy; but the real danger came, as with the Roman Empire, from an alien soldiery. Mutasim (833-842) had formed a body-guard of Turks, and these in time seized upon the real powers of government. They assassinated Mutawakkil, the son of Mutasim, in 861, and in the following century forced the caliphs to delegate the chief powers of government to their commander. Gradually the empire of the Abassides became contracted, until it was finally narrowed down to Bagdad and the surrounding territory. In 1258 Hulaku Khan, the Mongol ruler of Persia, burned Bagdad and put the ruling Caliph to death. Deprived of all political power, the Abbassides found refuge with the Mameluke rulers of Egypt, who paid them respect as the spiritual heads of the Mohammedan world. The last of the Abbassides, Mutawakkil III., died in 1538 at Cairo, where he was living under the protection of the Turkish Sultan. Consult: Muir, The Caliphate (London, 1891); Syed Ameer Ali, A ShortHistory of the Saracens (New York, 1899); and the more elaborate work, Weil, Geschichte derChalifen (Mannheim and Stuttgart, 1846-62).